This study is carried out to observe the flank wear in up and down milling in the case of peripheral milling. Equations for flank wear have been obtained by means of design of experiments and regression analysis. This research has shown that the time of inserts engagement has the largest influence on flank wear and the radial depth of cut the least in down milling. In up milling time of inserts engagement and cutting speed have the approximately equal influence. Hereinafter, flank wear correlated with the volume of the removed material for different processing parameters has been analysed. Observed from the viewpoint of removed material and flank wear, down milling is favorable compared to the up milling.